There is known a centrifugal casting process for rotating a cylindrical hollow mold about its own axis at a high speed to hold poured molten metal against the inner wall of the mold thereby to produce a hollow casting.
One known centrifugal casting apparatus which can be used to carry out the centrifugal casting process is disclosed in Japanese laid-open patent publication No. 57-94461, for example. As shown in FIG. 20 of the accompanying drawings, the disclosed centrifugal casting apparatus has a rotary mold 1, a pair of longitudinal guide rails 2 disposed axially on one side of the rotary mold 1, and a tube withdrawal device (not shown) disposed axially on the other side of the rotary mold 1.
A longitudinally movable carriage 3 is mounted on the longitudinal guide rails 2 for movement along the longitudinal guide rails 2 toward and away from the rotary mold 1. The longitudinally movable carriage 3 supports thereon a pair of transverse guide rails 4 extending perpendicularly to the longitudinal guide rails 2. When the longitudinally movable carriage 3 is disposed in a position remote from the rotary mold 1, the opposite ends of the transverse guide rails 4 are connected to respective pairs of shunting guide rails 5, 6.
A first transversely movable carriage 7 is disposed for movement on and between the shunting guide rails 5 and the transverse guide rails 4, and a second transversely movable carriage 8 is disposed for movement on and between the shunting guide rails 6 and the transverse guide rails 4. The first transversely movable carriage 7 supports a pouring device 9 thereon, and the second transversely movable carriage 8 supports thereon a brushing device (cleaning device) 10 and a spraying device 11 for spraying a facing material.
The disclosed centrifugal casting apparatus operates as follows: After a cast tube is pulled out of the rotary mold 1 by the non-illustrated tube withdrawal device, the longitudinally movable carriage 3 with the second transversely movable carriage 8 supported thereon is moved along the longitudinal guide rails 2 toward the rotary mold 1. At this time, the rotary mold 1 is rotated about its own axis, and the brushing device 10 on the second transversely movable carriage 8 brushes the inner wall surface of the rotary mold 1.
Then, while the longitudinally movable carriage 3 is moving away from the rotary mold 1, the spray device 11 on the second transversely movable carriage 8 sprays a facing material to coat the inner wall surface of the rotary mold 1. After the inner wall surface of the rotary mold 1 has been coated, the second transversely movable carriage 8 is retracted from the transverse guide rails 4 onto the shunting guide rails 6, and the first transversely movable carriage 7 is moved from the shunting guide rails 5 onto the transverse guide rails 4.
The longitudinally movable carriage 3 with the first transversely movable carriage 7 supported thereon is moved along the longitudinal guide rails 2 toward the rotary mold 1. The pouring device 6 mounted on the first transversely movable carriage 7 then pours a molten metal into the rotary mold 1. Then, the rotary mold 1 is rotated about its own axis to form and solidify the molten metal into a cast tube, which is subsequently pulled out of the rotary mold 1 by the tube withdrawal device.
The disclosed centrifugal casting apparatus is disadvantageous in that since the brushing device 10, the spraying device 11, and the pouring device 9 are disposed parallel to each other on axially one side of the rotary mold 1, the brushing device 10 and the spraying device 11 are susceptible to the heat of the pouring device 9, and hence their positioning accuracy tends to be lowered. Particularly if the cast tube is small in diameter and long, then the brushing device 10 and the spraying device 11 are liable to interfere with the pouring device 9.
The tube withdrawal device which is disposed axially on the other side of the rotary mold 1 is relatively long compared with the axial length of the rotary mold 1. Therefore, the centrifugal casting apparatus takes up a relatively large installation space and is poorly space efficient.
In order to perform an efficient centrifugal casting process, it is necessary in some applications to use two or more rotary molds 1 at the same time, each combined with the brushing device 10, the spraying device 11, the pouring device 9, and the tube withdrawal device. Such a scheme is problematic in that the entire facility needs a considerably large installation space and is highly costly to install and run.